The present invention relates to a manually guided implement, such as a brush cutter, power chain saw, or the like, that has an air-cooled internal combustion engine for driving a tool.
WO 99/45243 discloses a portable brush cutter for mowing grass, and has an air-cooled internal combustion engine that drives the cutting tool with its crankshaft. Between the crankshaft of the internal combustion engine and the tool is a centrifugal clutch that below certain engine speeds separates the drive mechanism via the engine from the tool. Fixedly held on the crankshaft is the flywheel portion of the centrifugal clutch, whereby the centrifugal bodies deflect under the influence of centrifugal forces when certain speeds are exceeded, whereby the centrifugal bodies close the clutch and the torque of the engine is transferred through the tool.
To cool the internal combustion engine, a fan wheel is fixedly held on the crankshaft and carries, on that suction side that faces away from the internal combustion engine, a suction ring of vanes having a plurality of guide vanes. The fan wheel, by means of its suction ring of vanes, conveys cooling air that surrounds the implement to the internal combustion engine. In this connection, the cooling air is drawn in from the direction of the centrifugal clutch that is secured to the end of the driver of the crankshaft. The flywheel portion is fixedly connected with the crankshaft, as a result of which transfer of the torque to the tool is ensured via the centrifugal clutch. The fan wheel is secured through the driver of the crankshaft between the flywheel portion and the internal combustion engine.
It is therefore an object of the present invention to improve an implement of the aforementioned general type in such a way that the overall size and weight of the implement are reduced, thereby improving the portability of the implement.